Lighting apparatus with flexible OLED area illumination light source and fixture

ABSTRACT

Lighting apparatus includes a solid-state area illumination light source, having: a planar flexible substrate, a flexible organic light emitting diode (OLED) layer deposited on the flexible substrate, the organic light emitting diode layer including first and second electrodes for providing electrical power to the OLED layer, a flexible encapsulating cover covering the OLED layer, and first and second conductors electrically connected to the first and second electrodes, and extending beyond the encapsulating cover for making electrical contact to the first and second electrodes by an external power source, whereby the light source may be stored in a space saving planar configuration; and a lighting fixture for removably receiving and holding the light source in a curved 3 dimensional configuration, the lighting fixture including a support for holding the light source in the curved configuration and contacts for providing electrical contact between said first and second conductors and an external power source.

FIELD OF THE INVENTION

The present invention relates to the use of organic light emittingdiodes for area illumination.

BACKGROUND OF THE INVENTION

Solid-state lighting devices made of light emitting diodes areincreasingly useful for applications requiring robustness and long-life.For example, solid-state LEDs are found today in automotiveapplications. These devices are typically formed by combining multiple,small LED devices providing a point light source into a single moduletogether with glass lenses suitably designed to control the light as isdesired for a particular application (see, for example WO99/57945,published Nov. 11, 1999). These multiple devices are expensive andcomplex to manufacture and integrate into single area illuminationdevices. Moreover, LED devices provide point sources of light that arenot preferred for area illumination.

Conventional illumination devices such as incandescent or fluorescentlight bulbs are bulky, fragile, and problematic to handle and ship.Although the bulbs are filled with gas, the glass tubes are easilybroken and occupy substantial space, especially in comparison to theactual light emitting area or material of the device. The bulbs must becarefully packed and require a large volume for shipping.

Existing solid-state lighting elements may be planar and hence easy andcost-effective to ship but do not address the need for lighting elementsthat have a variety of conventional three-dimensional shapes as found,for example, in light bulbs for decorative lighting. It is also usefulif a lighting device is readily and safely replaced by consumers atminimal cost.

There is a need therefore for an improved, replaceable OLED areaillumination device having a simple construction using a singlesubstrate, is compatible with the existing lighting infrastructure, isefficient to ship, and provides a variety of three-dimensional shapes.

SUMMARY OF THE INVENTION

The need is met by providing lighting apparatus that includes asolid-state area illumination light source, having: a planar flexiblesubstrate, a flexible organic light emitting diode (OLED) layerdeposited on the flexible substrate, the organic light emitting diodelayer including first and second electrodes for providing electricalpower to the OLED layer, a flexible encapsulating cover covering theOLED layer, and first and second conductors electrically connected tothe first and second electrodes, and extending beyond the encapsulatingcover for making electrical contact to the first and second electrodesby an external power source, whereby the light source may be stored in aspace saving planar configuration; and a lighting fixture for removablyreceiving and holding the light source in a curved 3 dimensionalconfiguration, the lighting fixture including a support for holding thelight source in the curved configuration and contacts for providingelectrical contact between said first and second conductors and anexternal power source.

ADVANTAGES

The present invention has the advantage of providing a lightingapparatus having a light source that can be stored efficiently in aplanar configuration, thereby saving considerable storage space. Anotheradvantage is that the planar flexible light sources are not fragile andcan be packaged in thin, unpadded packaging.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a partial cross section of a prior art conventionalOLED illumination device;

FIG. 2 is a perspective view of a flexible area illumination lightsource, including a detail of the layer structure, according to oneembodiment of the present invention;

FIG. 3 is a perspective view of the flexible light source of FIG. 2shown in a curved configuration;

FIG. 4 is a perspective view of a lighting fixture for holding the lightsource of FIG. 3 in its curved configuration;

FIG. 5 is a top view of the lighting fixture and light source showingclips for holding the light source in the curved configuration;

FIG. 6 is a perspective view of a light source and lighting fixtureaccording to an alternative embodiment of the present invention;

FIG. 7 is a perspective view of an alternative embodiment of a lightsource useable according to the present invention;

FIG. 8 is a perspective view of a further alternative embodiment of alight source useable according to the present invention;

FIG. 9 is a perspective view of a lighting fixture holding a pluralityof flexible light sources according to a further alternative embodimentof the present invention;

FIG. 10 is a perspective view of a light source held in a spiralconfiguration according to the present invention;

FIG. 11 is a perspective view of a light source held in a conicalconfiguration according to the present invention;

FIG. 12 is a perspective view of a light source and lighting fixturehaving a standard base.

FIG. 13 is a perspective view of lighting apparatus according to thepresent invention including a light transmissive housing according toone embodiment of the present invention;

FIG. 14 is a perspective view of a stack of flexible light sourcesaccording to the present invention; and

FIG. 15 is a cross sectional view of an OLED light source as known inthe prior art.

It will be understood that the figures are not to scale since theindividual layers are too thin and the thickness differences of variouslayers too great to permit depiction to scale.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic diagram of a prior art OLED light source 10including an organic light emitting layer 12 disposed between twoelectrodes, e.g. a cathode 14 and an anode 16. The organic lightemitting layer 12 emits light upon application of a voltage from a powersource 18 across the electrodes. The OLED light source 10 typicallyincludes a substrate 20 such as glass or plastic. It will be understoodthat the relative locations of the anode 16 and cathode 14 may bereversed with respect to the substrate. The term OLED light sourcerefers to the combination of the organic light emitting layer 12, thecathode 14, the anode 16, and other layers described below.

Referring to FIG. 2, a solid-state area illumination light source,includes a planar flexible substrate 20, a flexible organic lightemitting diode (OLED) layer 12 deposited on the flexible substrate, theorganic light emitting diode layer including first and second electrodes14 and 16 for providing electrical power to the OLED layer, a flexibleencapsulating cover 30 covering the OLED layer, first and secondconductors 24 and 26 electrically connected to the first and secondelectrodes, and extending beyond the encapsulating cover 30 for makingelectrical contact to the first and second electrodes 14 and 16 by anexternal power source, whereby the light source may be stored in a spacesaving planar configuration. The encapsulating cover may be a coatedlayer or an additional layer of material affixed over the OLED layersand sealed at the edges of the devices. Light may be emitted eitherthrough the substrate or the cover, or both, if they are transparent.The OLED layers themselves are continuous over the substrate to form asingle contiguous light-emitting area. As shown in FIG. 3, the flexiblesubstrate 20 can be curved into a three dimensional form and, as shownin FIG. 4, inserted into an aperture 36 in a lighting fixture 34 forremovably receiving and holding the light source 10 in a curvedthree-dimensional configuration. The lighting fixture includes a support38 having clips 39 for holding the light source in the curvedconfiguration, and contacts 40 within the aperture 36 for providingelectrical contact between the first and second conductors and anexternal power source.

The support 38 may be transparent. In one embodiment of the presentinvention, the flexible substrate 20 can define a tab portion 21 thatmay include an orientation feature such as step 28 to insure that thelight source is inserted in the fixture in the correct orientation. Thetab portion 21 can be inserted into the aperture 36 of the fixture 34and the light source 10 shaped around the support 38. Alternatively,additional contacts may be included in the aperture or on either side ofthe flexible substrate using conductive vias to provide electricalcontact with the conductors regardless of the orientation in which thetab is inserted (not shown).

The flexible substrate 20 may be fastened to the support 38 with, forexample, an adhesive, hook loop fasteners, or a mechanical restraintsuch as a clip or detent. In applications where it is not required toemit light from both sides of the substrate, one or more of thesubstrate, cover, anode, or cathode may be opaque or reflective. Thelight source 10 may be physically inserted into or removed from thefixture by pushing or pulling the substrate 20 into or out of theaperture 36.

FIG. 5 shows a top view of the support 38 with clips 39 for holdingedges of the light source 10. To install the light source 10 in fixture34, the tab portion 21 is first inserted into the aperture 36. Next, thelight source 10 is wrapped around the support 38 and the edges of theflexible light source 10 are inserted under clips 39 as shown by arrowA.

Referring to FIG. 6, in another embodiment, the flexible substrate 20may define two tabs 21 and 22. The first and second conductors 24 and 26are each located on a respective tab portion and structured to fit intocomplementary apertures 36 and 36′ in a fixture 34. The fixture 34includes one or more fins 41 for supporting the flexible light source10.

Referring to FIG. 7 in a further embodiment, the substrate 20 does notdefine a physical protrusion but includes first and second conductors 24and 26 located on an edge of the substrate 20. FIG. 8 illustrates analternative arrangement wherein the first and second conductors 24 and26 are at opposite edges of the substrate 20. In the embodiments shownin FIGS. 7 and 8, the apertures in the lighting fixture are wide enoughto receive the entire edge of the substrate. Alternatively, the supportcan include clamps for holding two or more edges of the light source tobow the light source into a three-dimensional configuration, for examplea cylindrical configuration. The contacts in the lighting fixture may belocated in the clamps. A wide variety of other configurations arereadily designed, including rings or conical sections.

Referring to FIG. 9, an alternative fixture and support are shownwherein two light sources 10 are held in a common fixture 34. The halfcylinder configurations shown in FIGS. 6 and 9 are useful, for example,for under-shelf lighting.

FIG. 10 illustrates another embodiment wherein the body of the lightsource 10 has an elongated rectangular shape and is held in a spiralconfiguration by the fixture 34. Clips 39 are provided at both ends ofthe spiral for holding the light source. FIG. 11 shows an embodimentwherein the light source 10 is held in the shape of a cone by fixture34.

Referring to FIG. 4, the lighting fixture 34 can be adapted to connectthe OLED light source 10 to an external power source (such as a standardhousehold electrical grid, not shown). The fixture 34 may includepower-conditioning circuitry 50 to convert the electrical power from theexternal power source to a form suitable for powering the OLED lightsource 10. For example, the OLED light source 10 may require a rectifiedvoltage with a particular waveform and magnitude; the power conditioningcircuitry can provide the particular waveform using conventional powercontrol circuitry. The particular waveform may periodically reverse biasthe light emitting organic materials to prolong the life time of theOLED materials. The fixture may also include a switch (not shown) forcontrolling the power to the light source.

The brightness of the light source 10 may be controlled by varying thepower provided to the OLED. In particular, pulse-width modulationschemes well known in the art may be employed (see for example,EP1094436A2, published Apr. 25, 2001) and implemented by the powerconditioning circuitry 50. Alternatively, the amount of power providedto the light emitting area may be reduced, for example by reducing thevoltage or limiting the current supplied to the OLED. A brightnesscontrol switch may be integrated into the socket, for example withvariable resistance switch formed. The power source may be standard 110volt AC as found in North America, 220 volt AC as found in Europe, orother standard power configurations such as 24-, 12-, or 6-volt DC.

The OLED light source 10 can be provided as a standard element andfixtures 34 customized to markets with differing power systems. OLEDlight sources 10 may be provided with different shapes or otherattributes useful in specific applications and may be employed with acommon socket, thereby decreasing costs and improving usefulness of thelighting apparatus.

Referring to FIG. 12, the lighting fixture 34 may include a supportportion 38 and a standard light bulb base 44 such as a US standard screwtype lamp base as shown in FIG. 12, or a pin-type base (not shown). Awide variety of standard lamp bases are known in the prior art and maybe used with the fixture of the present invention.

Referring to FIG. 13, a transparent or translucent screen or housing 52may be provided around the OLED light source 10 to diffuse the light andprovide additional physical protection and cosmetic appeal. The housingmay take a variety of shapes, for example the shape of a standard lightbulb.

Referring to FIG. 14, the flexible light sources 10 may be stacked andpacked in a planar configuration for compact storage and shipment. Thiscompact packing arrangement significantly reduces the packing volumenecessary for traditional bulbs and provides a robust, sturdy means forstoring, transporting, and stocking the lighting light sources 10.

The present invention may be employed in a wide variety of conventionalapplications, for example in a table-top lamp, floor-lamp, ceiling lamp,or chandelier. The present invention may also be employed in portableillumination devices using DC power sources.

In a preferred embodiment, the Organic Light Emitting Diode layers (OLEDlayers) are composed of small molecule OLEDs as disclosed in but notlimited to U.S. Pat. No. 4,769,292, issued Sep. 6, 1988 to Tang et al.,and U.S. Pat. No. 5,061,569, issued Oct. 29, 1991 to VanSlyke et al.

OLED Element Architecture

There are numerous configurations of OLED elements wherein the presentinvention can be successfully practiced. A typical, non-limitingstructure is shown in FIG. 15 and is comprised of an anode layer 103, ahole-injecting layer 105, a hole-transporting layer 107, alight-emitting layer 109, an electron-transporting layer 111, and acathode layer 113. These layers are described in detail below. The totalcombined thickness of the organic layers is preferably less than 500 nm.A voltage/current source 250 is required to energize the OLED elementand conductive wiring 260 is required to make electrical contact to theanode and cathode. The TFT layers and associated wiring serve thesefunctions.

Substrate

Substrate 20 is preferably light transmissive but may also be opaque.Substrates for use in this case include, but are not limited to, verythin glass and plastics.

Anode

The anode layer 103 is preferably transparent or substantiallytransparent to the light emitted by the OLED layer(s). Commontransparent anode materials used in this invention are indium-tin oxide(ITO), indium-zinc oxide (IZO) and tin oxide, but other metal oxides canwork including, but not limited to, aluminum- or indium-doped zincoxide, magnesium-indium oxide, and nickel-tungsten oxide. In addition tothese oxides, metal nitrides, such as gallium nitride, and metalselenides, such as zinc selenide, and metal sulfides, such as zincsulfide, can be used in layer 103. When the anode is not transparent,the light transmitting characteristics of layer 103 are immaterial andany conductive material can be used, transparent, opaque or reflective.Example conductors for this application include, but are not limited to,gold, iridium, molybdenum, palladium, and platinum. Typical anodematerials, transmissive or otherwise, have a work function of 4.1 eV orgreater. Desired anode materials are commonly deposited by any suitablemeans such as evaporation, sputtering, chemical vapor deposition, orelectrochemical means. Anodes can be patterned using well-knownphotolithographic processes.

Hole-Injecting Layer (HIL)

It is often useful that a hole-injecting layer 105 be provided betweenanode 103 and hole-transporting layer 107. The hole-injecting materialcan serve to improve the film formation property of subsequent organiclayers and to facilitate injection of holes into the hole-transportinglayer. Suitable materials for use in the hole-injecting layer include,but are not limited to, porphyrinic compounds as described in U.S. Pat.No. 4,720,432, and plasma-deposited fluorocarbon polymers as describedin U.S. Pat. No. 6,208,075. Alternative hole-injecting materialsreportedly useful in organic EL devices are described in EP 0 891 121 A1and EP 1 029 909A1.

Hole-Transporting Layer (HTL)

The hole-transporting layer 107 contains at least one hole-transportingcompound such as an aromatic tertiary amine, where the latter isunderstood to be a compound containing at least one trivalent nitrogenatom that is bonded only to carbon atoms, at least one of which is amember of an aromatic ring. In one form the aromatic tertiary amine canbe an arylamine, such as a monoarylamine, diarylamine, triarylamine, ora polymeric arylamine. Exemplary monomeric triarylamines are illustratedby Klupfel et al. U.S. Pat. No. 3,180,730. Other suitable triarylaminessubstituted with one or more vinyl radicals and/or comprising at leastone active hydrogen containing group are disclosed by Brantley et alU.S. Pat. Nos. 3,567,450 and 3,658,520. A more preferred class ofaromatic tertiary amines are those which include at least two aromatictertiary amine moieties as described in U.S. Pat. Nos. 4,720,432 and5,061,569. Illustrative of useful aromatic tertiary amines include, butare not limited to, the following:

1,1-Bis(4-di-p-tolylaminophenyl)cyclohexane

1,1-Bis(4-di-p-tolylaminophenyl)-4-phenylcyclohexane

4,4′-Bis(diphenylamino)quadriphenyl

Bis(4-dimethylamino-2-methylphenyl)-phenylmethane

N,N,N-Tri(p-tolyl)amine

4-(di-p-tolylamino)-4′-[4(di-p-tolylamino)-styryl]stilbene

N,N,N′,N′-Tetra-p-tolyl-4-4′-diaminobiphenyl

N,N,N′,N′-Tetraphenyl-4,4′-diaminobiphenyl

N,N,N′,N′-tetra-1-naphthyl-4,4′-diaminobiphenyl

N,N,N′,N′-tetra-2-naphthyl-4,4′-diaminobiphenyl

N-Phenylcarbazole

4,4′-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl

4,4′-Bis[N-(1-naphthyl)-N-(2-naphthyl)amino]biphenyl

4,4″-Bis[N-(1-naphthyl)-N-phenylamino]-p-terphenyl

4,4′-Bis[N-(2-naphthyl)-N-phenylamino]biphenyl

4,4′-Bis[N-(3-acenaphthenyl)-N-phenylamino]biphenyl

1,5-Bis[N-(1-naphthyl)-N-phenylamino]naphthalene

4,4′-Bis[N-(9-anthryl)-N-phenylamino]biphenyl

4,4″-Bis[N-(1-anthryl)-N-phenylamino]-p-terphenyl

4,4′-Bis[N-(2-phenanthryl)-N-phenylamino]biphenyl

4,4′-Bis[N-(8-fluoranthenyl)-N-phenylamino]biphenyl

4,4′-Bis[N-(2-pyrenyl)-N-phenylamino]biphenyl

4,4′-Bis[N-(2-naphthacenyl)-N-phenylamino]biphenyl

4,4′-Bis[N-(2-perylenyl)-N-phenylamino]biphenyl

4,4′-Bis[N-(1-coronenyl)-N-phenylamino]biphenyl

2,6-Bis(di-p-tolylamino)naphthalene

2,6-Bis[di-(1-naphthyl)amino]naphthalene

2,6-Bis[N-(1-naphthyl)-N-(2-naphthyl)amino]naphthalene

N,N,N′,N′-Tetra(2-naphthyl)-4,4″-diamino-p-terphenyl

4,4′-Bis{N-phenyl-N-[4-(1-naphthyl)-phenyl]amino}biphenyl

4,4′-Bis[N-phenyl-N-(2-pyrenyl)amino]biphenyl

2,6-Bis[N,N-di(2-naphthyl)amine]fluorene

1,5-Bis[N-(1-naphthyl)-N-phenylamino]naphthalene

Another class of useful hole-transporting materials includes polycyclicaromatic compounds as described in EP 1 009 041. In addition, polymerichole-transporting materials can be used such as poly(N-vinylcarbazole)(PVK), polythiophenes, polypyrrole, polyaniline, and copolymers such aspoly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) also calledPEDOT/PSS.

Light-Emitting Layer (LEL)

As more fully described in U.S. Pat. Nos. 4,769,292 and 5,935,721, thelight-emitting layer (LEL) 109 of the organic EL element comprises aluminescent or fluorescent material where electroluminescence isproduced as a result of electron-hole pair recombination in this region.The light-emitting layer can be comprised of a single material, but morecommonly consists of a host material doped with a guest compound orcompounds where light emission comes primarily from the dopant and canbe of any color. The host materials in the light-emitting layer can bean electron-transporting material, as defined below, a hole-transportingmaterial, as defined above, or another material or combination ofmaterials that support hole-electron recombination. The dopant isusually chosen from highly fluorescent dyes, but phosphorescentcompounds, e.g., transition metal complexes as described in WO 98/55561,WO 00/18851, WO 00/57676, and WO 00/70655 are also useful. Dopants aretypically coated as 0.01 to 10% by weight into the host material.Iridium complexes of phenylpyridine and its derivatives are particularlyuseful luminescent dopants. Polymeric materials such as polyfluorenesand polyvinylarylenes (e.g., poly(p-phenylenevinylene), PPV) can also beused as the host material. In this case, small molecule dopants can bemolecularly dispersed into the polymeric host, or the dopant could beadded by copolymerizing a minor constituent into the host polymer.

An important relationship for choosing a dye as a dopant is a comparisonof the bandgap potential which is defined as the energy differencebetween the highest occupied molecular orbital and the lowest unoccupiedmolecular orbital of the molecule. For efficient energy transfer fromthe host to the dopant molecule, a necessary condition is that the bandgap of the dopant is smaller than that of the host material.

Host and emitting molecules known to be of use include, but are notlimited to, those disclosed in U.S. Pat. Nos. 4,768,292, 5,141,671,5,150,006, 5,151,629, 5,405,709, 5,484,922, 5,593,788, 5,645,948,5,683,823, 5,755,999, 5,928,802, 5,935,720, 5,935,721, and 6,020,078.

Metal complexes of 8-hydroxyquinoline and similar oxine derivativesconstitute one class of useful host compounds capable of supportingelectroluminescence, and are particularly suitable. Illustrative ofuseful chelated oxinoid compounds are the following:

CO-1: Aluminum trisoxine [alias, tris(8-quinolinolato)aluminum(III)]

CO-2: Magnesium bisoxine [alias, bis(8-quinolinolato)magnesium(II)]

CO-3: Bis[benzo{f}-8-quinolinolato]zinc (II)

CO-4:Bis(2-methyl-8-quinolinolato)aluminum(III)-μ-oxo-bis(2-methyl-8-quinolinolato)aluminum(III)

CO-5: Indium trisoxine [alias, tris(8-quinolinolato)indium]

CO-6: Aluminum tris(5-methyloxine) [alias,tris(5-methyl-8-quinolinolato) aluminum(III)]

CO-7: Lithium oxine [alias, (8-quinolinolato)lithium(I)]

CO-8: Gallium oxine [alias, tris(8-quinolinolato)gallium(III)]

CO-9: Zirconium oxine [alias, tetra(8-quinolinolato)zirconium(IV)]

Other classes of useful host materials include, but are not limited to:derivatives of anthracene, such as 9,10-di-(2-naphthyl)anthracene andderivatives thereof, distyrylarylene derivatives as described in U.S.Pat. No. 5,121,029, and benzazole derivatives, for example,2,2′,2″-(1,3,5-phenylene)tris[1-phenyl-1H-benzimidazole].

Useful fluorescent dopants include, but are not limited to, derivativesof anthracene, tetracene, xanthene, perylene, rubrene, coumarin,rhodamine, quinacridone, dicyanomethylenepyran compounds, thiopyrancompounds, polymethine compounds, pyrilium and thiapyrilium compounds,fluorene derivatives, periflanthene derivatives and carbostyrylcompounds.

Electron-Transporting Layer (ETL)

Preferred thin film-forming materials for use in forming theelectron-transporting layer 111 of the organic EL elements of thisinvention are metal chelated oxinoid compounds, including chelates ofoxine itself (also commonly referred to as 8-quinolinol or8-hydroxyquinoline). Such compounds help to inject and transportelectrons, exhibit high levels of performance, and are readilyfabricated in the form of thin films. Exemplary oxinoid compounds werelisted previously.

Other electron-transporting materials include various butadienederivatives as disclosed in U.S. Pat. No. 4,356,429 and variousheterocyclic optical brighteners as described in U.S. Pat. No.4,539,507. Benzazoles and triazines are also usefulelectron-transporting materials.

In some instances, layers 111 and 109 can optionally be collapsed into asingle layer that serves the function of supporting both light emissionand electron transport. These layers can be collapsed in both smallmolecule OLED systems and in polymeric OLED systems. For example, inpolymeric systems, it is common to employ a hole-transporting layer suchas PEDOT-PSS with a polymeric light-emitting layer such as PPV. In thissystem, PPV serves the function of supporting both light emission andelectron transport.

Cathode

Preferably, the cathode 113 is transparent and can comprise nearly anyconductive transparent material. Alternatively, the cathode 113 may beopaque or reflective. Suitable cathode materials have good film-formingproperties to ensure good contact with the underlying organic layer,promote electron injection at low voltage, and have good stability.Useful cathode materials often contain a low work function metal (<4.0eV) or metal alloy. One preferred cathode material is comprised of aMg:Ag alloy wherein the percentage of silver is in the range of 1 to20%, as described in U.S. Pat. No. 4,885,221. Another suitable class ofcathode materials includes bilayers comprising a thin electron-injectionlayer (EIL) and a thicker layer of conductive metal. The EIL is situatedbetween the cathode and the organic layer (e.g., ETL). Here, the EILpreferably includes a low work function metal or metal salt, and if so,the thicker conductor layer does not need to have a low work function.One such cathode is comprised of a thin layer of LiF followed by athicker layer of Al as described in U.S. Pat. No. 5,677,572. Otheruseful cathode material sets include, but are not limited to, thosedisclosed in U.S. Pat. Nos. 5,059,861; 5,059,862, and 6,140,763.

When cathode layer 113 is transparent or nearly transparent, metals mustbe thin or transparent conductive oxides, or a combination of thesematerials. Optically transparent cathodes have been described in moredetail in U.S. Pat. Nos. 4,885,211, 5,247,190, JP 3,234,963, U.S. Pat.Nos. 5,703,436, 5,608,287, 5,837,391, 5,677,572, 5,776,622, 5,776,623,5,714,838, 5,969,474, 5,739,545, 5,981,306, 6,137,223, 6,140,763,6,172,459, EP 1 076 368, and U.S. Pat. No. 6,278,236. Cathode materialsare typically deposited by evaporation, sputtering, or chemical vapordeposition. When needed, patterning can be achieved through many wellknown methods including, but not limited to, through-mask deposition,integral shadow masking as described in U.S. Pat. No. 5,276,380 and EP 0732 868, laser ablation, and selective chemical vapor deposition.

Deposition of Organic Layers

The organic materials mentioned above are suitably deposited through avapor-phase method such as sublimation, but can be deposited from afluid, for example, from a solvent with an optional binder to improvefilm formation. If the material is a polymer, solvent deposition isuseful but other methods can be used, such as sputtering or thermaltransfer from a donor sheet. The material to be deposited by sublimationcan be vaporized from a sublimator “boat” often comprised of a tantalummaterial, e.g., as described in U.S. Pat. No. 6,237,529, or can be firstcoated onto a donor sheet and then sublimed in closer proximity to thesubstrate. Layers with a mixture of materials can utilize separatesublimator boats or the materials can be pre-mixed and coated from asingle boat or donor sheet. Patterned deposition can be achieved usingshadow masks, integral shadow masks (U.S. Pat. No. 5,294,870),spatially-defined thermal dye transfer from a donor sheet (U.S. Pat.Nos. 5,851,709 and 6,066,357) and inkjet method (U.S. Pat. No.6,066,357). While all organic layers may be patterned, it is most commonthat only the layer emitting light is patterned, and the other layersmay be uniformly deposited over the entire device.

Optical Optimization

OLED layers used with this invention can employ various well-knownoptical effects in order to enhance its properties if desired. Thisincludes optimizing layer thicknesses to yield maximum lighttransmission, providing dielectric mirror structures, replacingreflective electrodes with light-absorbing electrodes, providinganti-glare or anti-reflection coatings over the device, providing apolarizing medium over the device, or providing colored, neutraldensity, or color conversion filters over the device. Filters,polarizers, and anti-glare or anti-reflection coatings may bespecifically provided over the cover or as part of the cover.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

 10 OLED light source  12 organic light emitting layer  14 cathode  16anode  18 power source  20 substrate  21 tab portion of substrate  22tab portion of substrate  30 encapsulating cover  24 first conductor  26second conductor  28 step  34 lighting fixture  36 aperture  36′aperture  38 support  39 clip  40 contact  41 light source support fin 44 standard lamp base  50 power conditioning circuitry  52 lighttransmissive housing 103 anode 105 hole-injecting layer 107hole-transporting layer 109 light-emitting layer 111electron-transporting layer 113 cathode layer 250 voltage/current source260 conductive wiring

What is claimed is:
 1. Lighting apparatus, comprising: a) a solid-statearea illumination light source, having: i) a planar flexible substrate,ii) a flexible organic light emitting diode (OLED) layer deposited onthe flexible substrate, the organic light emitting diode layer includingfirst and second electrodes for providing electrical power to the OLEDlayer, iii) a flexible encapsulating cover covering the OLED layer, andiv) first and second conductors electrically connected to the first andsecond electrodes, and extending beyond the encapsulating cover formaking electrical contact to the first and second electrodes by anexternal power source, whereby the light source may be stored in a spacesaving planar configuration; and b) a lighting fixture for removablyreceiving and holding the light source in a curved three-dimensionalconfiguration, the lighting fixture including a support for holding thelight source in the curved configuration and contacts for providingelectrical contact between said first and second conductors and anexternal power source.
 2. The lighting apparatus claimed in claim 1,wherein the curved configuration is cylindrical, spiral, or pyramidal.3. The lighting apparatus claimed in claim 1, wherein the light sourcedefines a body portion and one or more tab portions; the first andsecond conductors being located on the tab portion(s).
 4. The lightingapparatus claimed in claim 3, wherein the tab portion(s) include anorientation feature for orienting the light source in a socket.
 5. Thelighting apparatus claimed in claim 3, wherein the first and secondconductors are located on both sides of the tab portion, whereby thelight source can be inserted into a socket in either of twoorientations.
 6. The lighting apparatus claimed in claim 5, wherein thelight source defines tabs that are located at opposite edges of thesubstrate.
 7. The lighting apparatus claimed in claim 1, wherein thefirst and second conductors are located at one or more edges of thelight source.
 8. The lighting apparatus claimed in claim 7, wherein thefirst and second conductors are located at opposite edges of the lightsource.
 9. The lighting apparatus claimed in claim 1, wherein the lightsource emits light from one side of the flexible support and the firstand second conductors are located on an opposite side.
 10. The lightingapparatus claimed in claim 1, wherein the encapsulating cover is acoated layer.
 11. The lighting apparatus claimed in claim 1, wherein theOLED layer is continuous over the substrate.
 12. The lighting apparatusclaimed in claim 1, wherein the light source operates on standard power.13. The lighting apparatus claimed in claim 12, wherein the standardpower is selected from the group consisting of 110 volt AC, 220 volt AC,24 volt DC, 12 volt DC, and 6 volt DC.
 14. The lighting apparatusclaimed in claim 1, wherein the support is transparent.
 15. The lightingapparatus claimed claim 1, further comprising a transparent ortranslucent housing surrounding the light source.
 16. The lightingapparatus claimed in claim 1, further comprising a base adapted to bereceived by and make electrical contact with a standard electricaloutlet.
 17. The lighting apparatus claimed in claim 1, furthercomprising: a converter connected to the first and second conductors forconverting power from the external power source to a form useable by theOLED layer.
 18. The lighting apparatus claimed in claim 17, wherein theconverter converts AC line voltage to a voltage useable by the OLEDlayer.
 19. The lighting apparatus claimed in claim 1, further comprisinga reflector for directing light from the light source.
 20. The lightingapparatus claimed in claim 1, wherein the lighting apparatus is aceiling lamp.
 21. The lighting apparatus claimed in claim 1, wherein thelighting apparatus is a table lamp.
 22. The lighting apparatus claimedin claim 1, wherein the lighting apparatus is a floor lamp.
 23. Thelighting apparatus claimed in claim 1, wherein the flexible substrate istransparent, and light is emitted from the OLED layer through theflexible substrate.
 24. The lighting apparatus claimed in claim 1,wherein the encapsulating cover is transparent, and light is emittedfrom the OLED layer through the encapsulating cover.
 25. The lightingapparatus claimed in claim 1, wherein the light source emits light fromonly one side of the substrate and further includes a reflective layeron the other side of the substrate.
 26. The lighting apparatus claimedin claim 1, wherein the light source emits light through both thesubstrate and the encapsulating cover.
 27. The lighting apparatusclaimed in claim 1, wherein the light source has a rectangular shape andthe support includes clamps for holding two edges of the light source tobow the light source into a cylindrical configuration.
 28. The lightingapparatus claimed in claim 27, wherein the contacts are located in theclamps.
 29. The lighting apparatus claimed in claim 1, wherein the lightsource has an elongated rectangular shape and the support includes aframe and clamps for holding the light source in a spiral configurationabout the frame.
 30. The lighting apparatus claimed in claim 29, whereinthe contacts are located in the clamps.
 31. The lighting apparatusclaimed in claim 1, wherein the light source is has the shape of a ringsegment, and the support includes clamps for holding the light source ina conical configuration.
 32. The lighting apparatus claimed in claim 29,wherein the contacts are located in the clamps.
 33. A method ofproviding lighting, comprising the steps of: a) providing a customerwith a solid-state area illumination light source in a planarconfiguration, thereby saving storage space, the light source having: i)a planar flexible substrate, ii) a flexible organic light emitting diode(OLED) layer deposited on the flexible substrate, the organic lightemitting diode layer including first and second electrodes for providingelectrical power to the OLED layer, iii) a flexible encapsulating covercovering the OLED layer, and iv) first and second conductorselectrically connected to the first and second electrodes, and extendingbeyond the encapsulating cover for making electrical contact to thefirst and second electrodes by an external power source, whereby thelight source may be stored in a space saving planar configuration; b)providing a customer with a lighting fixture for removably receiving andholding the light source in a curved 3 dimensional configuration, thelighting fixture including a support for holding the light source in thecurved configuration and contacts for providing electrical contactbetween said first and second conductors and an external power source;and c) the customer installing the planar light source in the lightingfixture.
 34. The method claimed in claim 33, wherein a plurality oflight sources are stacked and packed in planar configuration for compactstorage and shipment.
 35. The method claimed in claim 33, wherein thecurved configuration is cylindrical, spiral, or pyramidal.
 36. Themethod claimed in claim 33, wherein the light source defines a bodyportion and one or more tab portions; the first and second conductorsbeing located on the tab portion(s).
 37. The method claimed in claim 36,wherein the tab portion(s) include an orientation feature for orientingthe light source in a socket.
 38. The method claimed in claim 36,wherein the first and second conductors are located on both sides of thetab portion, whereby the light source can be inserted into a socket ineither of two orientations.
 39. The method claimed in claim 33, whereinthe light source defines tabs that are located at opposite edges of thesubstrate.
 40. The method claimed in claim 33, wherein the first andsecond conductors are located at one or more edges of the light source.41. The method claimed in claim 40, wherein the first and secondconductors are located at opposite edges of the light source.
 42. Themethod claimed in claim 33, wherein the light source emits light fromone side of the flexible substrate and the first and second conductorsare located on an opposite side.
 43. The method claimed in claim 33,wherein the encapsulating cover is a coated layer.
 44. The methodclaimed in claim 33, wherein the OLED layer is continuous over thesubstrate.
 45. The method claimed in claim 33, wherein the light sourceoperates on standard power.
 46. The method claimed in claim 45, whereinthe standard power is selected from the group consisting of 110 volt AC,220 volt AC, 24 volt DC, 12 volt DC, and 6 volt DC.
 47. The methodclaimed in claim 33, wherein the support is transparent.
 48. The methodclaimed in claim 33, further comprising a transparent or translucenthousing surrounding the light source.
 49. The method claimed in claim33, further comprising a base adapted to be received by and makeelectrical contact with a standard electrical outlet.
 50. The methodclaimed in claim 33, further comprising a converter connected to thefirst and second conductors for converting power from the external powersource to a form useable by the OLED layer.
 51. The method claimed inclaim 50, wherein the converter converts AC line voltage to a voltageuseable by the OLED layer.
 52. The method claimed in claim 33, furthercomprising a reflector for directing light from the light source. 53.The method claimed in claim 33, wherein the lighting apparatus is aceiling lamp.
 54. The method claimed in claim 33, wherein the lightingapparatus is a table lamp.
 55. The method claimed in claim 33, whereinthe lighting apparatus is a floor lamp.
 56. The method claimed in claim33, wherein the flexible substrate is transparent, and light is emittedfrom the OLED layer through the flexible substrate.
 57. The methodclaimed in claim 33, wherein the encapsulating cover is transparent, andlight is emitted from the OLED layer through the encapsulating cover.58. The method claimed in claim 33, wherein the light source emits lightfrom only one side of the substrate and further includes a reflectivelayer on the other side of the substrate.
 59. The method claimed inclaim 33, wherein the light source emits light through both thesubstrate and the encapsulating cover.
 60. The method claimed in claim33, wherein the light source has a rectangular shape and the supportincludes clamps for holding two edges of the light source to bow thelight source into a cylindrical configuration.
 61. The method claimed inclaim 60, wherein the contacts are located in the clamps.
 62. The methodclaimed in claim 33, wherein the light source has an elongatedrectangular shape and the support includes a frame and clamps forholding the light source in a spiral configuration about the frame. 63.The method claimed in claim 62, wherein the contacts are located in theclamps.
 64. The method claimed in claim 33, wherein the light source hasthe shape of a ring segment, and the support includes clamps for holdingthe light source in a conical configuration.
 65. The method claimed inclaim 64, wherein the contacts are located in the clamps.